Position detection device and control method for position detection sensor

ABSTRACT

A position detection device includes a main body with a housing that encloses an electronic pen while the electronic pen is accommodated in an accommodation portion included in the housing, and a planar coil having a rectangular cross-sectional area and disposed adjacent to the accommodation portion at a position at which a direction perpendicular to the rectangular cross-sectional area of the planar coil crosses an axial direction of the electronic pen while the electronic pen is accommodated in the accommodation portion.

BACKGROUND 1. Technical Field of the

The present disclosure relates to a position detection device whichincludes a position detection sensor and is used as an inputting devicefor various information terminals and a control method for a positiondetection sensor used in the position detection device.

2. Description of the Related Art

A large number of mobile information terminals in which a touch panel isincorporated such as a high function mobile phone terminal calledsmartphone or a tablet personal computer (PC) have been provided. Atouch panel is an electronic part in which a display unit such as aliquid crystal display unit and a position detection device including aposition detection sensor or a position detection circuit are combined.The touch panel allows various operation inputs by a touch operation bya finger of a user or the like.

As a position detection sensor (hereinafter referred to simply assensor), a sensor of the capacitive type and a sensor of theelectromagnetic induction type are available. The capacitive type sensordetects a variation of the capacitance between an indicator and aplurality of conductors provided on the sensor to detect a positionindicated by the indicator. Since a finger of the user may be used asthe indicator, the sensor allows a touch input by a finger. Meanwhile,in the electromagnetic induction type sensor, a signal is transferredthrough electromagnetic induction between an electronic pen (positionindictor) for exclusive use, which has a built-in resonance circuitformed from an inductor element (coil) and a capacitor element(capacitor), and a loop coil group provided on the sensor side to detecta position indicated by the electronic pen. Since the electronic pen forexclusive use is used, a fine instruction input can be performed, andalso it is possible to input information according to a writing pressureby a writing pressure detection function of the electronic pen.

Also a mobile information terminal is available which includes a sensorof the hybrid type provided with both a sensor of the capacitive typeand a sensor of the electromagnetic induction type and compatible withboth an input by a finger of the user and a fine input by an electronicpen for exclusive use. In a mobile information terminal in which such ahybrid type sensor as just described is incorporated, many simpleoperations are performed by a touch operation by a finger of the user.Therefore, to normally keep a sensor of the electromagnetic inductiontype in an operative state is not preferable in that it accelerates theexhaustion of the battery.

Therefore, some mobile information terminals in which a sensor of thehybrid type is incorporated includes an accommodation portion for anelectronic pen in a housing such that, when an electronic pen isaccommodated in the accommodation portion, the sensor of theelectromagnetic induction type is kept in an inoperative state. In otherwords, when an electronic pen is accommodated in the accommodationportion for an electronic pen, operation only of the sensor of thecapacitive type is permitted. On the other hand, if no electronic pen isaccommodated in the accommodation portion for an electronic pen, atleast operation of the sensor of the electromagnetic induction type ispermitted. Since this makes it possible for the sensor of theelectromagnetic induction type to operate only when the electronic penis in a used state, power saving of the battery can be anticipated.

Conventionally, detection of whether or not an electronic pen isaccommodated in an accommodation portion for an electronic pen providedon a mobile information terminal is performed by such a mechanicalswitch as disclosed, for example, in FIG. 2 of Japanese Patent Laid-OpenNo. 1998-013893. Also it is known to incorporate a magnet in anelectronic pen and provide a magnetic sensor having a configuration of aHall element in a mobile information terminal such that detection ofwhether or not the electronic pen is accommodated in the accommodationportion is performed.

In recent years, it has been and is demanded for a mobile informationterminal and an electronic pen to have a waterproof specification so asto withstand its use outdoors on a rainy day or around a body of watersuch as a sea, a river or a lake. However, where a mechanical switch fordetecting whether or not such an electronic pen as described above isaccommodated is to be provided in an accommodation portion for anelectronic pen on a mobile information terminal, since a gap isgenerated at a portion which operates as the switch, it is difficult tohave the waterproof specification. Also, where a magnet is incorporatedin an electronic pen and a magnetic sensor is provided on a mobileinformation terminal side, the magnet incorporated in the electronic penhas an influence on the resonance circuit of the electronic pen, acircuit portion of the sensor side for position detection and so forthor a circuit portion of the mobile information terminal side has aninfluence on the magnetic sensor, which is not preferable.

Thus, it seems advisable to adopt such a countermeasure that a coil isdisposed in an accommodation portion for an electronic pen in such amanner as to cover a coil which is built in the electronic pen such thatit is detected through electromagnetic induction whether or not theelectronic pen is accommodated in the accommodation portion. Inparticular, as depicted in FIG. 10A, an accommodation portion 203 for anelectronic pen which has an opening 202 is provided on a housing of amobile information terminal 200 in which a touch panel 201 isincorporated, and a coil 204 is provided at a position of an inner wallof the accommodation portion 203 at which, when an electronic pen isaccommodated in the accommodation portion 203, the coil 204 covers acoil built in the electronic pen.

A case is considered in which an electronic pen 300 is accommodated intothe accommodation portion 203 for an electronic pen. In this case, theelectronic pen 300 is inserted into the inside of the coil 204 disposedin the accommodation portion 203 as indicated by an arrow mark in FIG.10B such that the coil 204 covers a coil 301 of the electronic pen 300.Then, a signal is transmitted from the coil 204 within a fixed period,and within a later fixed period, a signal from the coil 301 which is acomponent of a resonance circuit of the electronic pen 300 is received.In this case, if a transmission signal from the electronic pen 300 canbe received, then it can be detected that the electronic pen 300 isaccommodated in the accommodation portion 203.

However, to provide the coil 204 on the inner wall of the accommodationportion 203 for an electronic pen of the mobile information terminal 200as depicted in FIG. 10A complicates the fabrication process or maypossibly result in increase of the thickness of the mobile informationterminal. The fabrication process preferably is simplified as far aspossible, and in recent years, also it is demanded to further reduce thethickness of a mobile information terminal. Therefore, a mobileinformation terminal is demanded to satisfy the requirement also forreduction of the thickness.

BRIEF SUMMARY

Taking the foregoing into consideration, it is an object of the presentdisclosure to provide a position detection device and a control methodfor a position detection sensor which can be suitably applied to amobile information terminal and can achieve implementation of awaterproof specification, avoidance of complication of a fabricationprocess and further reduction in thickness of the mobile informationterminal and also reduction of power consumption.

In order to attain the object described above, according to the presentdisclosure, there is provided a position detection device having anaccommodation portion that accommodates therein an electronic pen havinga position indication coil wound in an axial direction of the electronicpen. A planar coil is disposed adjacent to the accommodation portion ata position at which a center axis direction of the planar coil crossesthe axial direction of the electronic pen while the electronic pen isaccommodated in the accommodation portion, and numbers of magneticfluxes, from among magnetic fluxes generated by the planar coil,interlinking in directions opposite to each other with the positionindication coil of the electronic pen are not equal to each other. Afirst control circuit controls a supply process in which a first signalis supplied to the planar coil and a reception process in which a secondsignal is received through the planar coil by electromagnetic inductionare performed alternately. A first detection circuit, in operation,detects a state regarding accommodation of the electronic pen in theaccommodation portion in accordance with a presence or an absence of thesecond signal received through the planar coil.

Such a configuration enables efficient transfer of a signal between theposition indication coil of the electronic pen accommodated in theaccommodation portion and the planar coil provided on the positiondetection device.

Further, supply of a signal to the planar coil and reception of a signalthrough the planar coil through electromagnetic induction are performedalternately by the first control circuit. While the electronic pen isaccommodated in the accommodation portion, transfer of the first signalis performed through electromagnetic induction between the planar coiland the position indication coil of the electronic pen accommodated inthe accommodation portion. Therefore, the accommodation state regardingaccommodation of the electronic pen in the accommodation portion,namely, whether or not the electronic pen is accommodated in theaccommodation portion, is detected by the first detection circuit inaccordance with a presence or an absence of the second signal receivedthrough the planar coil.

Consequently, detection of whether or not the electronic pen isaccommodated in the accommodation portion can be performed appropriatelywithout providing a mechanical switch, a magnetic sensor or a coilformed spirally in the accommodation portion for an electronic pen ofthe electronic apparatus. Besides, since the planar coil is used, it iseasy to implement a waterproof specification and complication of thefabrication process can be avoided and besides reduction in thickness ofa mobile information terminal can be anticipated. In particular,although the planar coil is formed by winding a coated wire on a board,since it is planar in shape, reliable waterproof work can be performedreadily by coating, for example, using a resist technology, an overallface of the planar coil with a resin material which does not block asignal. Further, even if waterproof work is applied, the thickness ofthe planar coil part does not increase significantly. Further, if asensor of the electromagnetic induction type for detecting a positionindicated by the electronic pen is rendered operative only when theelectronic pen is not accommodated in the accommodation portion and maybe used in high possibility, then also reduction of power consumption byan electronic apparatus in which the position detection device isincorporated can be anticipated.

According to the present disclosure, a position detection device and acontrol method for a position detection sensor which can be suitablyapplied to a mobile information terminal and can achieve, by using aplanar coil, implementation of a waterproof specification, avoidance ofcomplication of a fabrication process and further reduction in thicknessof the mobile information terminal and also reduction of powerconsumption can be implemented.

The above and other objects, features and advantages of the presentdisclosure will become apparent from the following description and theappended claims, taken in conjunction with the accompanying drawings inwhich like parts or elements denoted by like reference symbols.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view depicting an example of an electronic apparatusconfigured using an inputting device formed from a position detectiondevice according to one or more embodiments of the present disclosureand an electronic pen;

FIGS. 2A and 2B are views depicting an example of a configuration of anelectronic pen according to one or more embodiments of the presentdisclosure;

FIG. 3 is a block diagram depicting a general configuration of anelectronic pen and an example of a circuit configuration of a positiondetection device according to one or more embodiments of the presentdisclosure;

FIGS. 4A, 4B and 4C are views illustrating a positional relationshipbetween a planar coil and a coil of an electronic pen and magneticfluxes generated from the planar coil according to one or moreembodiments of the present disclosure;

FIG. 5 is a view illustrating a positional relationship between a coilof an electronic pen accommodated in an accommodation portion and aplanar coil according to one or more embodiments of the presentdisclosure;

FIG. 6 is a flow chart illustrating a process performed by a controllerof a position detection device according to one or more embodiments ofthe present disclosure;

FIG. 7 is a block diagram depicting a general configuration of anelectronic pen and an example of a circuit configuration of a positiondetection device according to one or more embodiments of the presentdisclosure;

FIG. 8 is a flow chart illustrating a process performed by a controllerof a position detection device according to one or more embodiments ofthe present disclosure;

FIG. 9 is a block diagram depicting a general configuration of anelectronic pen and an example of a circuit configuration of a positiondetection device according to one or more embodiments of the presentdisclosure; and

FIGS. 10A and 10B are views depicting an example of a conventionaldetection mechanism which performs detection of whether or not anelectronic pen is accommodated in an accommodation portion.

DETAILED DESCRIPTION

In the following description, a position detection device and a controlmethod for a position detection sensor according to embodiments of thepresent disclosure are described with reference to the accompanyingdrawings.

First Embodiment

[Particular Example of Electronic Apparatus]

An example of an electronic apparatus configured incorporating aninputting device including a position detection device according to thepresent disclosure and an electronic pen (pen type position indicator)for use with the position detection device is described with referenceto FIG. 1 . The electronic apparatus of the present example is a tabletPC or a high function mobile phone terminal which includes a displayunit such as, for example, a liquid crystal display (LCD) unit. Theelectronic apparatus includes an electronic apparatus main body 1 inwhich the position detection device is incorporated, and an electronicpen 2.

The electronic apparatus main body 1 is configured such that an LCDunit, two position detection sensors of detection types different fromeach other, a mother board and so forth are stacked (disposed in anoverlapping relationship with each other) between a housing 1A and afront panel 1F. In the present embodiment, of the two position detectionsensors of different detection types, one is a position detection sensorof the electromagnetic induction type and the other is a positiondetection sensor of the capacitive type.

An opening 1FW is provided in the front panel 1F. The opening 1FW is setto a size equal to that of a display region of a display screen of theLCD unit and that of an operation region for accepting an input by auser using the electronic pen 2 or the like. Further, an accommodationportion 11 for accommodating therein the electronic pen 2 hereinafterdescribed is provided in the housing 1A of the electronic apparatus mainbody 1 such that, when the electronic pen 2 is not used, the electronicpen 2 is accommodated in the accommodation portion 11.

The electronic pen 2 is used to input information through a positiondetection sensor of the magnetic induction type. The user takes out theelectronic pen 2 accommodated in the accommodation portion 11 asoccasion demands and perform a position indication operation on theoperation region 1FW using the electronic pen 2. The electronic pen 2 issuitably used to perform inputting of fine information such as, forexample, to input a figure or a picture.

Further, the electronic apparatus main body 1 has a position detectionsensor of the capacitive type incorporated therein such that, if theuser touches the operation region 1FW with a finger of a hand thereof,then such operations as rendering, inputting of a hand-writtencharacter, selection of an icon or a display button and so forth can beperformed.

It is assumed here that an operation is performed by the electronic pen2 on the operation region 1FW of the electronic apparatus main body 1.In this case, the position and the writing pressure of the operation bythe electronic pen 2 are detected by the position detection sensor ofthe electromagnetic induction type provided in the inside of theelectronic apparatus main body 1. A display control circuit(microcomputer) of the electronic apparatus main body 1 controls adisplay process on the display screen of the LCD unit in response to thedetected position and writing pressure.

Similarly, it is assumed that, in the electronic apparatus, an operationis performed on the operation region 1FW of the electronic apparatusmain body 1 by a finger of a hand or the like of the user. In this case,the position indicated by the finger or the like is detected by theposition detection sensor of the capacitive type provided in the insideof the electronic apparatus main body 1. Then, in response to thedetected indication position, the display control circuit of theelectronic apparatus main body 1 controls a display process on thedisplay screen of the LCD unit.

The electronic pen 2 interacts with the position detection sensor of theelectromagnetic induction type as described above and includes, althoughdetails are hereinafter described, a coil 21 and a capacitor (capacitorelement) which cooperate with each other to configure a resonancecircuit. The coil 21 transfers a signal to and from the positiondetection sensor and is a position indication coil. In the case of theelectronic apparatus main body 1 of the present embodiment, a planarcoil 160 is provided on the lower side of the accommodation portion 11at a position which comes in the proximity of the coil 21 built in theelectronic pen 2 when the electronic pen 2 is accommodated in theaccommodation portion 11 as depicted in FIG. 1 .

The planar coil 160 and the coil 21 of the electronic pen 2 can transfera signal through electromagnetic induction such that a state ofaccommodation of the electronic pen 2 in the accommodation portion 11can be detected in response to a presence or an absence of atransmission signal from the coil 21 of the electronic pen 2. In otherwords, it can be detected whether or not the electronic pen 2 isaccommodated in the accommodation portion 11. If the electronic pen 2 isaccommodated in the accommodation portion 11, then detection of aposition indicated by the electronic pen 2 is not performed using theposition detection sensor of the electromagnetic induction type therebyto implement reduction of power consumption by the electronic apparatusmain body 1.

Further, since the planar coil 160 is used, it is possible to preventgeneration of a gap more easily than in a case where a mechanical switchis provided for detection of the accommodation state of an electronicpen in the accommodation portion 11, and a waterproof specification canbe achieved readily. Further, different from an alternative case inwhich the accommodation state of an electronic pen in the accommodationportion 11 is detected by a magnetic sensor provided in the proximity ofthe accommodation portion 11 and a magnet mounted on the electronic pen,there is no possibility that a magnet may have an influence on theposition detection sensor or the like. Further, in comparison withanother alternative case in which the accommodation state of anelectronic pen in the accommodation portion 11 is detected by a spiralcoil provided in the accommodation portion 11, the fabrication processcan be simplified, and also reduction in thickness of the electronicapparatus main body 1 can be anticipated.

[Example of Configuration of Electronic Pen]

Now, an example of a configuration of the electronic pen 2 used toindicate a position on the position detection sensor of theelectromagnetic induction type incorporated in the electronic apparatusmain body 1 depicted in FIG. 1 is described. FIGS. 2A and 2B are viewsdepicting an example of a configuration of the electronic pen 2 of thepresent embodiment, and particularly, FIG. 2A is a cross sectional viewof the electronic pen 2 and FIG. 2B is a circuit diagram depicting anequivalent circuit of the electronic pen 2.

As depicted in FIGS. 2A and 2B, the electronic pen 2 is configured suchthat various components that perform an electronic pen function areincorporated in a housing 23. A ferrite core 22 is formed, for example,from a cylindrical member of a ferrite material and has a through-holeformed at a position including a center line of an axial directionthereof (e.g., a central axis). The through-hole is formed with apredetermined diameter (for example, diameter=1 mm) and extends in theaxial direction such that a bar-like core member 24 formed, for example,from a resin or the like is inserted therein.

The core member 24 is inserted in the through-hole of the ferrite core22 so as to extend through the ferrite core 22. In particular, the coremember 24 is longer than the length of the ferrite core 22 in the axialdirection. Further, a portion of the core member 24 inserted in thethrough-hole of the ferrite core 22 has a diameter a little smaller thanthe diameter of the through-hole such that the core member 24 canslidably move in the axial direction in the through-hole. It is to benoted that an end portion of the core member 24 which serves as a pentip has a diameter a little greater than the diameter of thethrough-hole of the ferrite core 22 and has a distal end portion formedin a semispherical shape such that it can move smoothly on an operationface of a touch panel or the like.

Further, as depicted in FIG. 2A, a portion of a predetermined length ofthe ferrite core 22 including the center in the axial direction is usedas a coil wound portion around which the coil 21 is wound along theaxial direction, and the portions of the ferrite core 22 on the oppositesides of the predetermined length portion are used as coil non-woundportions around which no coil is wound. In other words, when the ferritecore 22 is viewed in the axial direction, a portion from an end portionon the pen tip side to an end portion of the coil wound portion on thepen tip side is a first coil non-wound portion around which no coil iswound. Further, a portion of the ferrite core 22 from the other end ofthe coil wound portion to an end portion on the side opposite to the pentip side is a second coil non-wound portion around which the coil 21 isnot wound.

Extension wires (conductor lines) 21 a and 21 b from the opposite endsof the coil 21 wound around the ferrite core 22 are extended to aprinted board 26 hereinafter described on the inner side of the housing23 and connected to a capacitor Cf provided on the printed board 26.Consequently, a resonance circuit is configured from the coil 21 and thecapacitor Cf on the printed board 26 such that a signal can betransferred through electromagnetic induction between the resonancecircuit and the position detection device of the electromagneticinduction type hereinafter described.

A connection portion 25 is provided on the opposite side to the pen tipof the core member 24 and includes a molded portion 25A, a writingpressure detection portion 25B, a fitting portion 25C and a connectionterminal portion 25D. The connection portion 25 is a portion whichintegrally connects a pen tip side portion configured from the coil 21,ferrite core 22 and core member 24 and the printed board 26 and a boardprotection pipe 27 hereinafter described to each other. The moldedportion 25A is a portion formed cylindrically from a resin or the like,and an outer circumference of an end face of the molded portion 25A onthe ferrite core 22 side is a little greater than an outer circumferenceof the coil wound portion of the ferrite core 22. A recessed portion isprovided on the end face side of the molded portion 25A opposing to theferrite core 22 such that the second coil non-wound portion of theferrite core 22 is fitted in the recessed portion.

Further, a core member holding portion A1, a conductive rubber memberA2, a ring spacer A3, a dielectric member A4 and a terminal member A5are provided in the inside of the molded portion 25A as depicted in FIG.2A. The members mentioned are sandwiched by the molded portion 25A andthe fitting portion 25C hereinafter described and configure the writingpressure detection portion 25B for detecting a writing pressure.

In particular, the core member holding portion A1 is formed in a cupshape, for example, from hard rubber, and an end portion of the coremember 24 on the side opposite to the pen tip side is inserted in andheld by the core member holding portion A1. A bottom face portion of thecore member holding portion A1 on the opposite side to the core member24 is formed in a spherical shape. Thus, the core member holding portionA1 functions as a pressing portion for pressing the conductive rubbermember A2 in response to a writing pressure applied to the core member24.

The conductive rubber member A2 has a predetermined thickness and has asame shape and a same size as those of an opposing face of thedielectric member A4. Further, a face of the conductive rubber member A2on the pen tip side is opposed to the bottom face portion of the coremember holding portion A1 formed in a spherical shape while the otherface is opposed to one face of the dielectric member A4 with the ringspacer A3 interposed therebetween.

The ring spacer A3 is a member formed in a ring shape and provides a gapof a magnitude equal to the thickness of the ring spacer A3 between theconductive rubber member A2 and the face of the dielectric member A4 onthe pen tip side to separate them from each other. The dielectric memberA4 is formed from a substance having dielectricity superior toconductivity such as, for example, a ceramic material and behaves, for adirect current (DC) voltage, as an insulator which blocks electricity.The terminal member A5 having a predetermined area is provided in such amanner as to be pasted to the other face of the dielectric member A4. Avariable capacitor is configured from the conductive rubber member(first electrode) A2 and the terminal member (second electrode) A5between which the dielectric member A4 is sandwiched.

In particular, the core member 24 slidably moves upwardly and downwardlyalong the axial direction in response to the writing pressure applied tothe pen tip thereof. The core member holding portion A1 pushes theconductive rubber member A2 to move upwardly and downwardly in aninterlocked relationship with the sliding movement of the core member24. Since a gap is provided between the conductive rubber member A2 andthe dielectric member A4 by the ring spacer A3, the conductive rubbermember A2 moves toward and into contact with the dielectric member A4 tovary the contact area in response to the writing pressure applied to thecore member 24. Consequently, the capacitance between the conductiverubber member A2 and the terminal member A5 between which the dielectricmember A4 is sandwiched varies in response to the writing pressure. Itis to be noted that, when no writing pressure is applied, the conductiverubber member A2 is spaced from the dielectric member A4 due to thepresence of the ring spacer A3.

The conductor line connected to the conductive rubber member A2 and theconductor line connected to the terminal member A5 pass, for example,along the outer side of the molded portion 25A and the fitting portion25C and are connected to terminals of the connection terminal portion25D hereinafter described and further connected to an electronic circuitof the printed board 26 hereinafter described through the terminals ofthe connection terminal portion 25D. Consequently, the electroniccircuit of the printed board 26 can detect the writing pressure appliedto the core member 24 as a variation of the capacitance of the variablecapacitor configured in such a manner as described above.

In the present example, the writing pressure detection portion 25Bconfigured from the core member holding portion A1, conductive rubbermember A2, ring spacer A3, dielectric member A4 and terminal member A5is similar to a writing pressure detection unit of a known configurationdisclosed, for example, in Japanese Patent Laid-Open No. 1993-275283.Alternatively, the writing pressure detection portion 25B can beconfigured similarly to a writing pressure detection unit of a knownconfiguration disclosed in Japanese Patent Laid-Open No. 2011-186803.Also it is possible to configure the writing pressure detection portion25B using such a semiconductor element whose capacitance is variable inresponse to the writing pressure as disclosed, for example, in JapanesePatent Laid-Open No. 2013-161307.

The fitting portion 25C is a portion to fit with the board protectionpipe 27 hereinafter described. The fitting portion 25C is formed, forexample, in a substantially cylindrical shape from a resin or hardrubber and is fitted firmly and integrally with the molded portion 25A.Consequently, as described hereinabove, the core member holding portionA1, conductive rubber member A2, ring spacer A3, dielectric member A4and terminal member A5 are sandwiched by the molded portion 25A and thefitting portion 25C, and the writing pressure detection portion 25Bconfigured from the members just described is held stably in the housing23.

Further, a recessed portion is provided on the inner side of the fittingportion 25C such that a distal end portion of the printed board 26hereinafter described is fitted into the recessed portion. It is to benoted that the outer diameter of the fitting portion 25C is a littlegreater than the inner diameter of the board protection pipe 27 suchthat the fitting portion 25C can fit firmly with the board protectionpipe 27. Thus, where the board protection pipe 27 is fitted with thefitting portion 25C, the outer circumference of the board protectionpipe 27 coincides with the outer circumference of the fitting portion25C or the molded portion 25A.

The connection terminal portion 25D is a portion formed from two upperand lower plate portions connecting to the fitting portion 25C asdepicted in FIG. 2A. The plate portions sandwich therebetween theprinted board 26 hereinafter described. In this case, the distancebetween the two upper and lower plate portions is a little smaller thanthe thickness of the printed board 26 such that the two upper and lowerplate portions can sandwich the printed board 26 therebetween.

One of the two plate portions, for example, the upper side plate portionin FIG. 2A, is provided such that the terminal described hereinabove towhich the conductor lines from the conductive rubber member A2 and theterminal member A5 are connected extends from the upper side face to thelower side face of the upper side place portion surrounding an end faceof the upper side place portion on the circuit board side. Consequently,when the printed board 26 is inserted into the connection terminalportion 25D, the terminal of the upper side plate portion isautomatically connected to a terminal portion of the electronic circuitprovided on the printed board 26.

The printed board 26 is formed such that terminals to the electroniccircuit described hereinabove and various circuit parts configuring theelectronic circuit are mounted on an insulating board of a rectangularshape and wiring lines connecting the terminals and the circuit parts toeach other are provided. The various circuit parts include an integratedcircuit (IC) which functions as a control circuit, a plurality ofcapacitors Cf and so forth. The printed board 26 is accommodated in theinside of and protected by the board protection pipe 27 as depicted inFIG. 2A.

The board protection pipe 27 is formed using a metal, a carbon material,a synthetic resin or the like and is a hard pipe member which is lesslikely to bend or curve. The board protection pipe 27 has a core memberside opening and a rear end side opening at the opposite ends thereof.The core member side opening and the rear end side opening are openingportions extending in a direction crossing with the axial direction. Thefitting portion 25C of the connection portion 25 is inserted into andfitted with a portion of the board protection pipe 27 within apredetermined range from the core member side opening. Similarly, a pipelid 28 is inserted into and fitted with a portion of the boardprotection pipe 27 within a predetermined range from the rear end sideopening. Also the pipe lid 28 has a recessed portion provided thereon inwhich an end portion of the printed board 26 is to be inserted.

Consequently, the pen tip side portion in which the core member 24 isinserted in the ferrite core 22 having the coil 21 wound thereon, theconnection portion 25, the board protection pipe 27 in which the printedboard 26 is accommodated and the pipe lid 28 are connected integrallywith each other and accommodated in the housing 23 thereby to configurethe electronic pen 2.

The electronic pen 2 of the present embodiment is represented by anequivalent circuit depicted in FIG. 2B. In particular, the coil 21, thewriting pressure detection portion 25B having a configuration of avariable capacitor and the capacitor Cf on the printed board 26 areconnected in parallel to each other to configure a resonance circuit.Consequently, the electronic pen 2 can transmit and receive a signal toand from the position detection device which includes a positiondetector sensor of the electromagnetic induction type hereinafterdescribed.

Further, the electronic pen 2 of the present embodiment can transmit andreceive a signal to and from the planar coil 160, which is provided inthe proximity of the accommodation portion 11 of the electronicapparatus main body 1 in which the electronic pen 2 is accommodated,through electromagnetic induction. Consequently, the electronicapparatus main body 1 can appropriately detect whether or not theelectronic pen 2 is accommodated in the accommodation portion 11 and cancontrol, when the electronic pen 2 is accommodated in the accommodationportion 11, such that detection of an indication position by theposition detection device of the electromagnetic induction type is notperformed.

[Outline of Coordinate Detection Sensor of Electromagnetic InductionTransfer Type]

Now, an example of a circuit configuration of an embodiment of aposition detection device 100 of the electromagnetic induction transfertype which performs detection of an indication position and a writingpressure using the electronic pen 2 of the electromagnetic inductiontransfer type described hereinabove with reference to FIGS. 2A and 2B.FIG. 3 is a block diagram depicting a general configuration of theelectronic pen 2 and an example of a circuit configuration of theposition detection device 100. As described hereinabove, the electronicapparatus main body 1 incorporates the position detection device of theelectromagnetic induction type and the position detection device of thecapacitive coupling type, and the position detection device 100 depictedin FIG. 3 is incorporated as the position detection device of theelectromagnetic induction type in the electronic apparatus main body 1.

The electronic pen 2 has the pen tip side portion in which the coremember 24 extends through the through-hole provided in the ferrite core22 around which the coil 21 is wound, the through-hole extending at aposition including the axis of the ferrite core 22 along the axis, asdescribed hereinabove with reference to FIG. 2A. Further, as describedhereinabove with reference to FIGS. 2A and 2B, the coil 21 of theelectronic pen 2 is connected to the writing pressure detection portion25B and the capacitor Cf of the printed board 26 so as to configure theresonance circuit.

Meanwhile, the position detection device 100 is configured from aposition detection circuit (main sensor unit) for detecting a positionindicated by the electronic pen 2 and a writing pressure applied to theelectronic pen 2, and an accommodation sensor circuit (sub sensor unit)for detecting whether or not the electronic pen 2 is accommodated in theaccommodation portion 11. First, a configuration of the positiondetection circuit is described.

The position detection circuit includes a position detection sensor 110which is a main sensor. The position detection sensor 110 is configuredby providing an X-axis direction loop coil group 111 and a Y-axisdirection loop coil group 112 in a stacked state. Each of the loop coilgroups 111 and 112 is configured, for example, from 40 or morerectangular loop coils. The loop coils configuring each of the loop coilgroups 111 and 112 are disposed in a juxtaposed relationship at equaldistances and in a successively overlapping relationship with eachother.

The position detection sensor 110 configured from the loop coil groups111 and 112 is connected to a circuit including a reception amplifierAP, an oscillation circuit unit 120, a position detection circuit 130, awriting pressure detection circuit unit 140 and a control circuit (e.g.,a central processing unit, controller, or microprocessor storinginstructions for performing the processing described below) 150 througha selection circuit 113 and a switch circuit SW1. The selection circuit113 is connected to the X-axis direction loop coil group 111 and theY-axis direction loop coil group 112. The selection circuit 113 selectsan arbitrary one of the loop coils of the two loop coil groups 111 and112 under the control of the control circuit 150 hereinafter described.

The oscillation circuit 120 is configured from an oscillator 121 and acurrent driver 122. The oscillator 121 generates an alternating current(AC) signal of a frequency f0 and supplies the AC signal to the currentdriver 122 and a synchronous detector 141 of the writing pressuredetection circuit 140 hereinafter described. The current driver 122converts the AC signal supplied thereto from the oscillator 121 intocurrent and sends out the current to the switch circuit SW1. The switchcircuit SW1 changes over the connection destination (a transmission sideterminal T or a reception side terminal R) to which a loop coil selectedby the selection circuit 113 under the control of the control circuit150 hereinafter described. Of the connection destinations, thetransmission side terminal T is connected to the current driver 122 andthe reception side terminal R is connected to the reception amplifierAP.

An induced voltage generated in a loop coil selected by the selectioncircuit 113 (a reception signal from the electronic pen 2) is sent outto the reception amplifier AP through the selection circuit 113 and theswitch circuit SW1. The reception amplifier AP amplifies the inducedvoltage supplied thereto from the loop coil and sends out the amplifiedinduced voltage to a detector 131 of the position detection circuit unit130 and the synchronous detector 141 of the writing pressure detectioncircuit unit 140.

The detector 131 of the position detection circuit 130 detects aninduced voltage generated in a loop coil, namely, a reception signal,and sends out the detected reception signal to a low-pass filter 132.The low-pass filter 132 has a cutoff frequency sufficiently lower thanthe frequency f0, and converts an output signal of the detector 131 intoa DC signal and sends out the DC signal to a sample and hold circuit133. The sample and hold circuit 133 holds a voltage value at apredetermined timing of the output signal of the low-pass filter 132,particularly at a predetermined timing within a reception period, andsends out the held voltage value to an analog to digital (A/D)conversion circuit 134. The A/D conversion circuit 134 converts ananalog output of the sample and hold circuit 133 into a digital signaland sends out the digital signal to the control circuit 150.

On the other hand, the synchronous detector 141 of the writing pressuredetection circuit 140 synchronously detects an output signal of thereception amplifier AP with an AC signal from the oscillator 121 andsends out a signal of a level according to a phase difference betweenthe signals to a low-pass filter 142. The low-pass filter 142 has acutoff frequency sufficiently lower than the frequency f0, and convertsan output signal of the synchronous detector 141 into a DC signal andsends out the DC signal to a sample and hold circuit 143. The sample andhold circuit 143 holds a voltage value at a predetermined timing of theoutput signal of the low-pass filter 142 and sends out the held voltagevalue to an A/D conversion circuit 144. The A/D conversion circuit 144converts an analog output of the sample and hold circuit 143 into adigital signal and sends out the digital signal to the control circuit150.

The control circuit 150 controls the components which configure theposition detection circuit (main sensor unit) and the accommodationsensor circuit (sub sensor unit) hereinafter described. In particular,the control circuit 150 controls selection of a loop coil by theselection circuit 113, changeover of the switch circuit SW1, and timingsof the sample and hold circuits 133 and 143. The processing control unit150 controls the X-axis direction loop coil group 111 and the Y-axisdirection loop coil group 112 to transmit a signal (electromagneticinduction signal) within a fixed transmission duration on the basis ofinput signals from the A/D conversion circuits 134 and 144.

In each of the loop coils of the X-axis direction loop coil group 111and the Y-axis direction loop coil group 112, an induced voltage isgenerated by a signal transmitted thereto from the electronic pen 2. Thecontrol circuit 150 calculates a coordinate value in each of the X-axisdirection and the Y-axis direction of a position indicated by theelectronic pen 2 on the basis of the voltage values of the inducedvoltages generated in the loop coils. Further, the control circuit 150detects a writing pressure on the basis of a phase difference between atransmitted signal and a received signal.

Now, a configuration of the accommodation sensor circuit (sub sensorunit) is described. As described hereinabove, the accommodation sensorcircuit includes the planar coil 160 which is a sub sensor provided inthe proximity of the accommodation portion 11 for the electronic pen 2.The planar coil 160 is connected at one end portion thereof to theoscillation circuit 120 or the ground through a switch circuit SW2.Further, the planar coil 160 is connected at the other end portionthereof to a sample and hold circuit 170 such that an output of thesample and hold circuit 170 is supplied to the control circuit 150.

The switch circuit SW2 and the sample and hold circuit 170 arecontrolled by a control signal from the control circuit 150. The controlcircuit 150 forms a control signal for alternately providing atransmission period and a reception period. Here, the transmissionperiod is a period within which current from the oscillation circuit 120is supplied to the planar coil 160 such that an induced voltage isgenerated in the coil 21 of the electronic pen 2 through electromagneticinduction and within which the control signal from the control circuit150 indicates an on state (high level). On the other hand, the receptionperiod is a period within which current from the capacitor Cf issupplied to the coil 21 of the electronic pen 2 such that an inducedvoltage (reception signal) generated in the planar coil 160 throughelectromagnetic induction is detected and within which the controlsignal from the control circuit 150 indicates an off state (low level).

In this manner, the control circuit 150 forms a control signal whichindicates an on state within a transmission period and indicates an offstate within a reception period, and supplies the control signal to theswitch circuit SW2 and further to the sample and hold circuit 170through an inversion circuit IV. Accordingly, while a control signal foran on state is supplied to the switch circuit SW2, a control signal foran off state is supplied to the sample and hold circuit 170. Incontrast, while a control signal for an off state is supplied to theswitch circuit SW2, a control signal for an on state is supplied to thesample and hold circuit 170.

Consequently, within a transmission period within which the controlsignal from the control circuit 150 indicates an on state, the switchcircuit SW2 is changed over to a terminal Ta side, and current from theoscillation circuit 120 is supplied to the planar coil 160. On the otherhand, within a transmission period within which the control signal fromthe control circuit 150 indicates an on state, since the sample and holdcircuit 170 is supplied with a control signal for an off state by thefunction of the inversion circuit IV, the sample and hold circuit 170does not operate within this period but is grounded though not depicted.

Accordingly, within a transmission period, since magnetic fluxes aregenerated from current flowing through the planar coil 160, if the coil21 of the electronic pen 2 is positioned in the proximity of the planarcoil 160, then current flows through the coil 21 and an induced voltageis generated across the coil 21. In other words, transmission of asignal from the planar coil 160 to the coil 21 of the electronic pen 2is performed through electromagnetic induction. Since the resonancecircuit is formed from the coil 21 and the capacitor Cf in theelectronic pen 2, charge according to the induced voltage is accumulatedinto the capacitor Cf.

On the other hand, within a reception period within which the controlsignal from the control circuit 150 indicates an off state, the switchcircuit SW2 is changed over to a terminal Ra side and one end portion ofthe planar coil 160 is grounded. In this case, within a transmissionperiod within which the control signal from the control circuit 150indicates an off state, the sample and hold circuit 170 is supplied witha control signal for an on state by the function of the inversioncircuit IV and operates within this period.

As described hereinabove, since, within a transmission period, charge isaccumulated into the capacitor Cf configuring the resonance circuit ofthe electronic pen 2, within a reception period, the charge accumulatedin the capacitor Cf flows as current to the coil 21 of the electronicpen 2 such that magnetic fluxes are generated in the coil 21. Therefore,the magnetic fluxes generated by the coil 21 of the electronic pen 2 actto cause current to flow through the planar coil 160 positioned in theproximity of the coil 21 of the electronic pen 2, whereupon an inducedvoltage is generated across the planar coil 160. In other words,transmission of a signal from the coil 21 of the electronic pen 2 to theplanar coil 160 is performed through electromagnetic induction. Thesample and hold circuit 170 samples the induced voltage generated acrossthe planar coil 160 within a reception period and holds the sampledvoltage value and then transmits the sampled voltage value to thecontrol circuit 150.

Consequently, if the voltage value from the sample and hold circuit 170is equal to or higher than a fixed value, then it can be recognized thattransfer of a signal between the planar coil 160 and the coil 21 of theelectronic pen 2 through electromagnetic induction is performed. In thiscase, the control circuit 150 can detect that the electronic pen 2 isaccommodated in the accommodation portion 11. In contrast, if thevoltage value from the sample and hold circuit 170 is lower than thefixed value, then it can be recognized that transfer of a signal betweenthe planar coil 160 and the coil 21 of the electronic pen 2 throughelectromagnetic induction is not performed. In this case, the controlcircuit 150 can detect that the electronic pen 2 is not accommodated inthe accommodation portion 11.

Then, if the control circuit 150 detects that the electronic pen 2 isaccommodated in the accommodation portion 11, then it controls thecomponents so as not to perform a detection process of an indicationposition and a writing pressure through the position detection sensor110. In contrast, if the control circuit 150 detects that the electronicpen 2 is not accommodated in the accommodation portion 11, then itcontrols the components so as to perform a detection process of anindication position and a writing pressure through the positiondetection sensor 110. Consequently, it is possible to avoid, when suchdetection is not required, driving of the position detection sensor 110thereby to achieve reduction of the power consumption.

[Positional Relationship Between Coil of Electronic Pen and Planar Coil]

FIGS. 4A to 4C illustrate a positional relationship between the planarcoil 160 and the coil 21 of the electronic pen 2 and a magnetic fieldand magnetic fluxes generated by the planar coil 160. The coil 21 builtin the electronic pen 2 is wound along the axial direction indicated bya broken line on the electronic pen 2 in FIGS. 4A and 4B as describedhereinabove. Further, the planar coil 160 provided in the proximity ofthe accommodation portion 11 in which the electronic pen 2 isaccommodated is provided in the proximity of the coil 21 of theelectronic pen 2 accommodated in the accommodation portion 11 such thatthe planar coil 160 extends substantially in parallel to the axis of theelectronic pen 2 as depicted in FIGS. 4A and 4B.

As depicted in FIGS. 4A to 4C, an aggregate of fluxes of a magneticfield generated by current flowing in a direction of arrow marks alongconductors Ca1 and Ca2 positioned on a short side Ca side of the planarcoil 160 is denoted by reference symbol Mfa. Similarly, an aggregate offluxes of a magnetic field generated by current flowing in a directionof arrow marks along conductors Cb1 and Cb2 positioned on a short sideCb side of the planar coil 160 is denoted by reference symbol Mfb.

Then, the planar coil 160 is disposed such that, if the electronic pen 2is accommodated into the accommodation portion 11 of the housing 1A,then the planar coil 160 is positioned in the proximity of the coil 21of the electronic pen 2. In this case, the magnetic fluxes Mfa and Mfbgenerated by the planar coil 160 interlink with the coil 21 of theelectronic pen 2, whereupon current is induced in the coil 21 and chargeis accumulated into the capacitor Cf connected to the coil 21. Here, theinterlink signifies that the magnetic fluxes Mfa and Mfb sneak likechains through the coil 21.

It is assumed here as illustrated in FIG. 4A that the number of themagnetic fluxes Mfa interlinking with a right side portion of the coil21 with reference to the center in the axial direction (directionindicated by a broken line in FIG. 4A) of the coil 21 provided in theelectronic pen 2 and the number of the magnetic fluxes Mfb interlinkingwith a left side portion of the coil 21 are equal to each other. Themagnetic fluxes Mfa and the magnetic fluxes Mfb act in directionsopposite to each other on the coil 21 of the electronic pen 2 (indirections in which the magnetic fluxes Mfa and Mfb advance in aninterlinking relationship with the coil 21) as illustrated in FIG. 4A.

In other words, the magnetic fluxes Mfa generated on the right side bythe planar coil 160 and the magnetic fluxes Mfb generated on the leftside by the planar coil 160 act such that current components of theopposite directions to each other are generated in the coil 21 of theelectronic pen 2. Therefore, the current components generated in thecoil 21 of the electronic pen 2 through electromagnetic induction canceleach other, and current does not flow efficiently through the coil 21.Consequently, sufficient charge cannot be accumulated into the capacitorCf.

Accordingly, in this case, even if supply of current to the planar coil160 stops, since charge is not accumulated in the capacitor Cf of theelectronic pen 2, current does not flow into the coil 21 of theelectronic pen 2 and a magnetic field (magnetic flux) is not generatedin the coil 21. Therefore, current does not flow through the planar coil160 in response to magnetic fluxes generated in the coil 21 of theelectronic pen 2, and consequently, even if the electronic pen 2 isaccommodated into the accommodation portion 11, this cannot be detected.

Therefore, in the present embodiment, the planar coil 160 is disposedsuch that the magnetic fluxes Mfa generated in the right side portion ofthe planar coil 160 or the magnetic fluxes Mfb generated in the leftside portion interlink more with the coil 21 of the electronic pen 2accommodated in the accommodation portion 11 than the other magneticfluxes. For example, the planar coil 160 is displaced to the right sidewith respect to the coil 21 of the electronic pen 2 accommodated in theaccommodation portion 11 in such a manner as depicted in FIG. 4B suchthat the magnetic fluxes Mfb generated in the left side portion of theplanar coil 160 interlink more with the coil 21 of the electronic pen 2.Consequently, current can be generated efficiently in the coil 21 of theelectronic pen 2 through electromagnetic induction in response to themagnetic fluxes Mfb generated in the left side portion of the planarcoil 160, and charge can be accumulated sufficiently into the capacitorCf.

Naturally, the planar coil 160 may be displaced reversely to the leftside with respect to the coil 21 of the electronic pen 2 accommodated inthe accommodation portion 11 such that the magnetic fluxes Mfa generatedin the right side portion of the planar coil 160 may interlink more withthe coil 21 of the electronic pen 2. It is to be noted that, in thiscase, since there is the possibility that the magnetic fluxes Mfbgenerated in the left side portion of the planar coil 160 may have aninfluence on some other portion of the electronic pen 2, it is necessaryto take this point into consideration.

Further, in the present embodiment, the planar coil 160 has aconfiguration of a flexible printed circuit (FPC) as depicted in FIG.4C. In particular, the planar coil 160 is formed such that a coil formedon a plane from a conductive metal such as, for example, copper ispasted to a thin and soft base film 171 having an insulating propertysuch as, for example, polyimide. Consequently, the coil can be fixed onthe same plane such that the turns of the coil are not spaced away fromeach other upwardly or downwardly (in a direction of the center axis) ornot displaced from each other on the plane.

A magnetic metal plate 172 and a conductive metal shield 173 areprovided on the lower side of the planar coil 160 in a center axisdirection indicated by the line with the arrow in FIG. 4C. The magneticmetal plate 172 strengthens magnetic fluxes generated by the planar coil160 and acts, in the example depicted in FIGS. 4A to 4C, so as to liftthe magnetic fluxes efficiently from the lower side to the upper side inthe axial direction of the planar coil 160. The conductive metal shield173 is provided so as to prevent electromagnetic waves arriving from theoutside from having an influence on the planar coil 160. In this manner,in the present embodiment, transfer of a signal through electromagneticinduction can be performed efficiency between the coil 21 of theelectronic pen 2 accommodated in the accommodation portion 11 and theplanar coil 160.

FIG. 5 is a view more particularly illustrating a positionalrelationship between the coil 21 of the electronic pen 2 accommodated inthe accommodation portion 11 and the planar coil 160 in the presentembodiment. As depicted in FIG. 5 , the width of the area in which theplanar coil 160 is formed is, for example, equal to or greater than 6 mmsuch that the coil 21 of the electronic pen 2 can be positioned on theinner side of the planar coil 160.

It is assumed that the electronic pen 2 advances in the longitudinaldirection of the planar coil 160 above the planar coil 160 such that thedistal end (pen tip) of the core member 24 of the electronic pen 2 ispositioned at a position at which it abuts with an end portion Tb of theplanar coil 160. A case is assumed in which, in the case just described,magnetic fluxes Mfa and Mfb generated by the planar coil 160 are equalin number and interlink with a half of the coil 21 on the pen tip sideand the other half on the opposite side to the pen tip side withreference to the center in the axial direction of the coil 21 of theelectronic pen 2 similarly as in the case depicted in FIG. 4A.

In this case, the position of the electronic pen 2 accommodated in theaccommodation portion 11 is set so as to be spaced by a distance atleast equal to or greater than 1 mm from the end portion Tb of theplanar coil 160 toward the other end portion side as depicted in FIG. 5. If the electronic pen 2 is displaced by a distance equal to or greaterthan 1 mm from the end portion Tb of the planar coil 160 in this manner,then the magnetic fluxes Mfb can interlink more with the coil 21 of theelectronic pen 2 similarly as in the case of the example depicted inFIG. 4B. Consequently, current can be efficiently generated in the coil21 of the electronic pen 2 through electromagnetic induction in responseto the magnetic fluxes generated by the planar coil 160.

Further, a rectangular area 160Ar which has a length equal to the sum ofthe length L1 from the end portion Tb of the planar coil 160 to a pointat which the distal end of the core member 24 of the electronic pen 2 ispositioned and the length L2 spaced by 30 mm or more from the distal endof the core member 24 of the electronic pen 2 to the rear end side ofthe electronic pen 2 and has a length of 6 mm or more in the verticaldirection in FIG. 5 is determined as an area in which a magnetic metalplate or a conductive metal shield is to be provided. Accordingly, inthe case of the example depicted in FIG. 5 , the rectangular area 160Arat least of a vertical dimension of 6 mm and a horizontal dimension of31 mm is an area in which the planar coil 160 is to be provided and inwhich a magnetic metal plate or a conductive metal shield is to beprovided.

Further, if the positional relationship between the planar coil 160 andthe coil 21 of the electronic pen 2 is set in such a manner asillustrated in FIG. 5 , then transfer of a signal throughelectromagnetic induction can be performed efficiently between theplanar coil 160 and the coil 21 of the electronic pen 2. It is to benoted that by what distance the distal end of the core member 24 of theelectronic pen 2 is to be spaced from the end portion Tb of the planarcoil 160 may be determined by determining a position at which transferof a signal can be performed efficiently through electromagneticinduction, for example, by an experiment.

[Particular Example of Control by Position Detection Device 100]

Now, a particular example of processing control by the control circuitunit 150 of the position detection device 100 having the configurationdescribed hereinabove with reference to FIG. 3 is described. FIG. 6 is aflow chart illustrating a process performed by the control circuit 150of the position detection device 100 after the main power supply to theelectronic apparatus main body 1 is turned on. To the process of theflow chart depicted in FIG. 6 , the “control method for a positiondetection sensor” of the disclosure disclosed herein is applied.

The control circuit 150 first performs an accommodation detectionprocess for detecting whether or not the electronic pen 2 isaccommodated in the accommodation portion 11 using the planar coil 160which is a sub sensor (S101). In particular, the control circuit 150forms a control signal which indicates alternate repetitions of an onperiod and an off period and supplies the control signal to the switchcircuit SW2 and also to the sample and hold circuit 170 through theinversion circuit IV. Consequently, to the switch circuit SW2 and thesample and hold circuit 170, control signals of the opposite phases toeach other are supplied.

Accordingly, if a control signal for an on state is supplied to theswitch circuit SW2, then a control signal for an off state is suppliedto the sample and hold circuit 170. In this case, the switch circuit SW2is changed over to the terminal Ta side, and the sample and hold circuit170 is rendered inoperative and grounded. Therefore, current from theoscillation circuit 120 is supplied to the planar coil 160, whereuponmagnetic fluxes are generated in the planar coil 160. Consequently,current flows into the coil 21 of the electronic pen 2 throughelectromagnetic induction and a signal is transmitted.

In contrast, if a control signal for an off state is supplied to theswitch circuit SW2, then a control signal for an on state is supplied tothe sample and hold circuit 170. In this case, the switch circuit SW2 ischanged over to the terminal Ra side and grounded while the sample andhold circuit 170 is rendered operative. Therefore, current flows throughthe planar coil 160 through electromagnetic induction by an influence ofmagnetic fluxes generated by the coil 21 of the electronic pen 2,whereupon an induced voltage is generated. The induced voltage issampled and held by the sample and hold circuit 170.

Transmission and reception of a signal through electromagnetic inductionthrough the planar coil 160 are repeated in this manner. Then, if aninduced voltage of a value equal to or higher than a fixed valuedetermined in advance is detected, then it can be detected that theelectronic pen 2 is accommodated in the accommodation portion 11. Incontrast, if an induced voltage of a value equal to or higher than thefixed value determined in advance is not detected, then it can bedetected that the electronic pen 2 is not accommodated in theaccommodation portion 11.

Then, the control circuit 150 decides based on a result of theaccommodation detection process at S101 whether or not the electronicpen 2 is accommodated in the accommodation portion 11 (S102). It isassumed that it is decided at S102 that the electronic pen 2 is notaccommodated in the accommodation portion 11. In this case, since theelectronic pen 2 is in a used state, the control circuit 150 controlsthe position detection sensor 110 which is a main sensor to functionthereby to start a detection process of a position indicated by theelectronic pen 2 and a writing pressure through the position detectionsensor 110 (S103).

In particular, at S103, the control circuit 150 supplies control signalsto control the selection circuit 113, switch circuit SW1, sample andhold circuit 133 of the position detection circuit 130 and sample andhold circuit 143 of the writing pressure detection circuit 140. In thiscase, the control circuit 150 starts a process for successivelyselecting loop coils to be used for transmission and reception of asignal from within the loop coil groups 111 and 112 and alternatelychanging over between a transmission period within which current fromthe oscillation circuit 120 is to be supplied to the selected loop coiltherefor and a reception period within which a signal from theelectronic pen 2 is to be received through the selected loop coiltherefor. Then, within the reception period, detection of a positionindicated by the electronic pen 2 on the position detection sensor 110and detection of a writing pressure applied to the electronic pen 2through contact of the electronic pen 2 with the position detectionsensor 110 are performed by the position detection circuit 130 and thewriting pressure detection circuit 140.

Thereafter, the control circuit 150 executes, at a suitable timing, anaccommodation detection process for detecting whether or not theelectronic pen 2 is accommodated in the accommodation portion 11 usingthe planar coil 160 which is a sub sensor similarly as in the processexecuted at step S101 (S104). Then, the control circuit 150 decides, onthe basis of a result of the accommodation detection process at S104,whether or not the electronic pen 2 is accommodated in the accommodationportion 11 (S105) similarly as in the decision process executed at S102.

If it is decided in the decision process at S105 that the electronic pen2 is not accommodated in the accommodation portion 11, then the controlcircuit 150 repeats the processes beginning at S104. Consequently, for aperiod until the electronic pen 2 is accommodated into the accommodationportion 11, detection of a position indicated by the electronic pen 2and detection of a writing pressure applied to the electronic pen 2 areperformed continuously through the position detection sensor 110 whichis a main sensor.

On the other hand, it is assumed that it is decided in the decisionprocess at S105 that the electronic pen 2 is accommodated in theaccommodation portion 11. In this case, since the electronic pen 2 isnot in a used state, the control circuit 150 ends the detection processof an indication position and a writing pressure through the positiondetection sensor 110 which is a main sensor (S106).

In particular, at S106, the control circuit 150 stops supply of thecontrol signals to the selection circuit 113, switch circuit SW1, sampleand hold circuit 133 of the position detection circuit 130 and sampleand hold circuit 143 of the writing pressure detection circuit 140.Consequently, operation of the components is stopped, and the processthrough the position detection sensor 110 for performing detection of aposition indicated by the electronic pen 2 and detection of a writingpressure applied to the electronic pen 2 is ended.

Thereafter, the control circuit 150 decides whether or not the mainpower supply to the electronic apparatus main body 1 is off (S107). Ifit is decided in the decision process at S107 that the main power supplyis not off, then the control circuit 150 repeats the processes beginningat S101. On the other hand, if it is decided in the decision process atS107 that the main power supply is off, then the control circuit 150performs a predetermined ending process such as to stop supply of powerto the control circuit 150 (S108), thereby ending the processillustrated in FIG. 6 .

On the other hand, it is assumed that it is decided in the decisionprocess at S102 described hereinabove that the electronic pen 2 isaccommodated in the accommodation portion 11. Also in this case, sincethe electronic pen 2 is not in a used state, the control circuit 150does not perform detection of an indication position and a writingpressure through the position detection sensor 110 which is a mainsensor and decides whether or not the main power supply to theelectronic apparatus main body 1 is off (S107).

If it is decided in the decision process at S107 that the main powersupply is not off, then the control circuit 150 repeats the processesbeginning at S101. On the other hand, if it is decided in the decisionprocess at S107 that the main power supply is off, then the controlcircuit 150 performs a predetermined ending process such as to stopsupply of power to the control circuit 150 (S108), thereby ending theprocess illustrated in FIG. 6 .

In this manner, the control circuit 150 can appropriately detect whetheror not the electronic pen 2 is accommodated in the accommodation portion11 using the planar coil 160 which is a sub sensor. Then, only when theelectronic pen 2 is not accommodated in the accommodation portion 11 butis in a used state, the control circuit 150 can perform detection of aposition indicated by the electronic pen 2 and detection of a writingpressure applied to the electronic pen 2 through the position detectionsensor 110 which is a main sensor. Consequently, when the electronic pen2 is in a state in which it is accommodated in the accommodation portion11, since none of detection of a position indicated by the electronicpen 2 and detection of a writing pressure applied to the electronic pen2 through the position detection sensor 110 is performed, reduction ofthe power consumption can be anticipated.

Further, since the planar coil 160 is used as a sub sensor, for example,if a resist technology is used to cover the planar coil 160 with awaterproof sheet of a resin or the like, then the gap can be closed upfully and a waterproof specification can be achieved readily. Further,since the planar coil 160 is used, in comparison with an alternativecase in which a coil of a spiral shape is used, complication of thefabrication process can be avoided and also reduction in thickness canbe anticipated.

Second Embodiment

FIG. 7 is a block diagram depicting a general configuration of theelectronic pen of the embodiments and a position detection device 100Aof a second embodiment. Also the position detection device 100A of thesecond embodiment described below is of the electromagnetic inductiontype similarly to the position detection device 100 of the firstembodiment and is incorporated and used together with the positiondetection device of the capacitive coupling type in the electronicapparatus main body 1 depicted in FIG. 1 . Accordingly, also theposition detection device 100A of the second embodiment is operated bythe electronic pen 2 described hereinabove with reference to FIGS. 1 and2 .

Therefore, also the position detection device 100A of the present secondembodiment has a function for detecting whether or not the electronicpen 2 is accommodated in the accommodation portion 11. However, asdepicted in FIG. 7 , the position detection device 100A of the presentsecond embodiment does not include the accommodation sensor circuitconfigured from the planar coil 160, switch circuit SW2, sample and holdcircuit 170 and inversion circuit IV provided in the position detectiondevice 100 of the first embodiment.

The position detection device 100A of the present second embodiment isconfigured from a planar coil 160A as a sub sensor and a positiondetection circuit (main sensor unit) which functions also as anaccommodation sensor circuit. The position detection circuit unit has abasic configuration similar to that of the position detection device 100of the first embodiment described hereinabove. Therefore, in FIG. 7which is a block diagram of the position detection device 100A of thesecond embodiment, like elements to those of the position detectiondevice 100 of the first embodiment depicted in FIG. 3 are denoted bylike reference symbols, and overlapping detailed description of them isomitted herein to avoid redundancy.

Also the planar coil 160A in the present second embodiment is providedin the proximity of the accommodation portion 11 for the electronic pen2 provided on the electronic apparatus main body 1 similarly as in thecase of the planar coil 160 in the first embodiment. Also in theposition detection device 100A of the second embodiment, magnetic fluxesof different directions generated by the planar coil 160A do not actuniformly on the coil 21 of the electronic pen 2 accommodated in theaccommodation portion 11. In particular, also in the position detectiondevice 100A of the second embodiment, the positional relationshipbetween the coil 21 of the electronic pen 2 accommodated in theaccommodation portion 11 and the planar coil 160A disposed in theproximity of the accommodation portion 11 is set to such a relationshipas described hereinabove with reference to FIGS. 4B and 5 .

As depicted in FIG. 7 , in the position detection device 100A of thesecond embodiment, the planar coil 160A serving as a sub sensor isconnected at one end thereof to a selection circuit 113A and grounded atthe other end thereof. The configuration of the other part is similar tothat of the position detection device 100 of the first embodimentdepicted in FIG. 3 .

Therefore, in the position detection device 100A of the present secondembodiment, when it is to be detected whether or not the electronic pen2 is accommodated in the accommodation portion 11, the control circuit150 controls the selection circuit 113A to select the planar coil 160A.Then, the control circuit 150 controls the switch circuit SW1 to performchangeover between a period (transmission period) within which currentfrom the oscillation circuit 120 is supplied to the planar coil 160A andanother period (reception period) within which a voltage generatedacross the planar coil 160A is detected through electromagneticinduction. Within the reception period, the control circuit 150 controlsthe position detection circuit 130 to function so as to detect whetheror not the planar coil 160A receives a signal from the coil 21 of theelectronic pen 2 through electromagnetic induction thereby to detectwhether or not the electronic pen 2 is accommodated in the accommodationportion 11.

On the other hand, detection of a position indicated by the electronicpen 2 and detection of a writing pressure applied to the electronic pen2 are performed quite similarly to those in the case of the positiondetection device 100 of the first embodiment described hereinabove. Inparticular, the control circuit 150 supplies control signals to theselection circuit 113A, switch circuit SW1, sample and hold circuit 133of the position detection circuit 130 and sample and hold circuit 143 ofthe writing pressure detection circuit 140 to control them.

In this case, the control circuit 150 successively selects a loop coilto be used for each of transmission and reception of a signal from andby the loop coil groups 111 and 112 and performs a process forperforming alternate changeover between a transmission period withinwhich current from the oscillation circuit 120 is supplied to theselected loop coil and a reception period within which a signal from theelectronic pen 2 is received through the selected loop coil. Then,within the reception period, the control circuit 150 performs detectionof a position indicated by the electronic pen 2 on the positiondetection sensor 110 and detection of a writing pressure applied to theelectronic pen 2 by contact of the electronic pen 2 with the positiondetection sensor 110 through the position detection circuit 130 and thewriting pressure detection circuit 140.

In this manner, also in the case of the position detection device 100Aof the present second embodiment, it is possible to perform detection ofwhether or not the electronic pen 2 is accommodated in the accommodationportion 11 using the planar coil 160A serving as a sub sensor. Further,also in the case of the position detection device 100A of the presentsecond embodiment, it is possible to perform detection of a positionindicated on the position detection sensor 110 by the electronic pen 2and detection of a writing pressure applied to the electronic pen 2.

[Particular Example of Control in Position Detection Device 100A]

Now, a particular example of processing control by the control circuit150 of the position detection device 100A of the second embodimenthaving the configuration described above with reference to FIG. 7 isdescribed. FIG. 8 is a flow chart illustrating a process executed by thecontrol circuit 150 of the position detection device 100A of the secondembodiment after the main power supply to the electronic apparatus mainbody 1 is turned on. To the process of the flow chart depicted in FIG. 8, the “control method for a position detection sensor” of the disclosuredisclosed herein is applied.

The control circuit 150 first uses the planar coil 160A which is a subsensor to execute an accommodation detection process for detectingwhether or not the electronic pen 2 is accommodated in the accommodationportion 11 (S201). In particular, the control circuit 150 controls theselection circuit 113A to select the planar coil 160A and maintain theselection. Then, the control circuit 150 forms a control signal forrepeating alternate changeover between an on period and an off periodand supplies the control signal to the switch circuit SW1. Further,within an off period, the control circuit 150 controls the sample andhold circuit 133 of the position detection circuit 130 to operate.

Then, if transmission and reception of a signal through electromagneticinduction through the planar coil 160A are repeated until an inducedvoltage of a value equal to or higher than a fixed value determined inadvance is detected through the position detection circuit 130 within areception period, then it can be detected that the electronic pen 2 isaccommodated in the accommodation portion 11. In contrast, if an inducedvoltage of a value equal to or higher than the fixed value determined inadvance is not detected through the position detection circuit 130within a reception period, then it can be detected that the electronicpen 2 is not accommodated in the accommodation portion 11.

Then, the control circuit 150 decides on the basis of a result of theaccommodation detection process at S201 whether or not the electronicpen 2 is accommodated in the accommodation portion 11 (S202). It isassumed that it is decided at S202 that the electronic pen 2 is notaccommodated in the accommodation portion 11. In this case, since theelectronic pen 2 is in a used state, the control circuit 150 controlsthe position detection sensor 110 which is a main sensor to function soas to start a detection process of a position indicated by theelectronic pen 2 and a writing pressure through the position detectionsensor 110 (S203). The process at S203 is similar to that at S103performed in the position detection device 100 of the first embodimentdepicted in FIG. 6 .

Thereafter, at a predetermined timing, the control circuit 150 controlsthe selection circuit 113A to change over so as to select the planarcoil 160A and executes an accommodation detection process for detectingwhether or not the electronic pen 2 is accommodated in the accommodationportion 11 (S204). In particular, the process at S204 is similar to thatexecuted at S201. Further, the predetermined timing is such a timingafter, in the detection process of an indication position and a writingpressure started at S203, the detection process of one cycle determinedin advance ends but before the detection process of a next cycle isstarted, for example.

It is to be noted that the detection process of one cycle determined inadvance signifies such a detection process as one unit of processes, forexample, after a detection process is started until an indicationposition and a writing pressure are detected successfully or until ascanning process using all loop coils of the position detection sensor110 is completed. Accordingly, when the detection process of one cycleis completed, a new detection process is started. Therefore, if anaccommodation detection process of the electronic pen 2 is performedwithin a period between a detection process of a certain one cycle and adetection process of a next one cycle, then the accommodation detectionprocess of the electronic pen 2 can be performed without having aninfluence on the detection process of a position indicated by theelectronic pen 2 and a writing pressure.

Then, the control circuit 150 decides on the basis of a result of theaccommodation detection process at S204 whether or not the electronicpen 2 is accommodated in the accommodation portion 11 similarly as inthe decision process performed at S202 (S205).

If it is decided in the decision process at S205 that the electronic pen2 is not accommodated in the accommodation portion 11, then the controlcircuit 150 repeats the processes beginning at S204. Consequently,within a period until the electronic pen 2 is accommodated into theaccommodation portion 11, detection of a position indicated by theelectronic pen 2 and detection of a writing pressure applied to theelectronic pen 2 through the position detection sensor 110 which is amain sensor are performed continuously.

On the other hand, it is assumed that it is decided in the decisionprocess at S205 that the electronic pen 2 is accommodated in theaccommodation portion 11. In this case, since the electronic pen 2 isnot in a used state, the control circuit 150 controls the positiondetection sensor 110 which is a main sensor to end the detection processof an indication position and a writing pressure (S206).

In particular, at S206, the control circuit 150 controls the selectioncircuit 113A to maintain the state in which the planar coil 160A isselected such that transmission and reception of a signal through theplanar coil 160A are repeated. Accordingly, at S206, any one of the loopcoils configuring the X-axis direction loop coil group 111 and the loopcoils configuring the Y-axis direction loop coil group 112 is notselected. Consequently, since the detection process of a positionindicated by the electronic pen 2 using the position detection sensor110 which is a main sensor is not performed, the power consumption canbe reduced significantly.

Further, in this case, since the oscillation circuit 120, positiondetection circuit 130 and control circuit 150 are kept in an operativestate, if the electronic pen 2 is taken out from the accommodationportion 11, then this can be also detected. It is to be noted that, whenthe electronic pen 2 is accommodated in the accommodation portion 11,since the writing pressure detection circuit 140 need not operate,operation of the writing pressure detection circuit 140 may be stopped.

Thereafter, the control circuit 150 decides whether or not the mainpower supply to the electronic apparatus main body 1 is off (S207). Ifit is decided in the decision process at S207 that the main power supplyis not off, then the processes beginning at S201 are repeated. On theother hand, if it is decided in the decision process at S207 that themain power supply is off, then the control circuit 150 performs such apredetermined ending process as to stop supply of power to the controlcircuit 150 (S208), thereby ending the process illustrated in FIG. 8 .

Further, it is assumed that it is decided in the decision process atS202 described hereinabove that the electronic pen 2 is accommodated inthe accommodation portion 11. Also in this case, since the electronicpen 2 is not in a used state, the control circuit 150 does not performdetection of an indication position and a writing pressure through theposition detection sensor 110 which is a main sensor but decides whetheror not the main power supply to the electronic apparatus main body 1 isoff (S207).

If it is decided in the decision process at S207 that the main powersupply is not off, then the processes beginning at S201 are repeated. Onthe other hand, if it is decided in the decision process at S207 thatthe main power supply is off, then the control circuit 150 performs sucha predetermined ending process as to stop supply of power to the controlcircuit 150 (S208), thereby ending the process illustrated in FIG. 8 .

In this manner, also in the case of the position detection device 100Aof the present second embodiment, the control circuit 150 canappropriately detect whether or not the electronic pen 2 is accommodatedin the accommodation portion 11 using the planar coil 160A which is asub sensor. Then, only when the electronic pen 2 is not accommodated inthe accommodation portion 11 but is in a used state, detection of aposition indicated by the electronic pen 2 and detection of a writingpressure applied to the electronic pen 2 through the position detectionsensor 110 which is a main sensor can be performed. Consequently, whenthe electronic pen 2 is accommodated in the accommodation portion 11,since none of detection of a position indicated by the electronic pen 2and detection of a writing pressure applied to the electronic pen 2through the position detection sensor 110 is performed, reduction of thepower consumption can be anticipated.

Further, since the planar coil 160A is used as a sub sensor, forexample, if a waterproof sheet is used, then the gap can be closed upfully and a waterproof specification can be achieved readily. Further,since the planar coil 160A is used, in comparison with an alternativecase in which a coil formed in a spiral shape is used, complication ofthe fabrication process can be avoided and also reduction in thicknesscan be anticipated.

Third Embodiment

FIG. 9 is a block diagram depicting a position detection device 100B ofa third embodiment. Also the position detection device 100B of the thirdembodiment described below is of the electromagnetic induction typesimilarly to the position detection devices 100 and 100A of the firstand second embodiments and is incorporated and used together with theposition detection device of the capacitive coupling type in theelectronic apparatus main body 1 depicted in FIG. 1 . Accordingly, alsothe position detection device 100B of the third embodiment is operatedby the electronic pen 2 described hereinabove with reference to FIGS. 1and 2 .

Therefore, also the position detection device 100B of the present thirdembodiment has a function for detecting whether or not the electronicpen 2 is accommodated in the accommodation portion 11. However,different from the position detection devices 100 and 100A of the firstand second embodiments described hereinabove, the position detectiondevice 100B of the present third embodiment does not include any of theplanar coils 160 and 160A for exclusive use as a sub sensor.

The position detection device 100B of the present third embodiment isconfigured such that one of the loop coils in the loop coil groups 111and 112 configuring the position detection sensor 110 is used also as aplanar coil as a sub sensor as depicted in FIG. 9 . In the case of theexample depicted in FIG. 9 , it is depicted that the Xath loop coil inthe X-axis direction loop coil group 111 is used also as a planar coilas a sub sensor. In particular, in the case of the position detectiondevice 100B of the third embodiment, the Xath loop coil of the X-axisdirection loop coil group 111 is extended so as to form a planar coilportion which functions as a sub sensor in the proximity of theaccommodation portion 11.

Accordingly, in the case of the position detection device 100B of thepresent third embodiment, the position detection circuit 130 has aconfiguration which functions also as an accommodation sensor circuit.Further, the position detection device 100B is configured similarly tothe position detection device 100 of the first embodiment describedhereinabove except the Xath loop coil of the X-axis direction loop coilgroup 111. Therefore, in FIG. 9 which is a block diagram of the positiondetection device 100B of the third embodiment, like elements to those ofthe position detection device 100 of the first embodiment depicted inFIG. 3 are denoted by like reference symbols, and overlapping detaileddescription of them is omitted herein to avoid redundancy.

Thus, in the present third embodiment, also the planar coil portionformed by extending the Xath loop coil and functioning as a sub sensorin the proximity of the accommodation portion 11 has a positionalrelationship with the coil 21 of the electronic pen 2 accommodated inthe accommodation portion 11 similar as in the case of the firstembodiment. In other words, also in the position detection device 100Bof the present third embodiment, the positional relationship between thecoil 21 of the electronic pen 2 accommodated in the accommodationportion 11 and the planar coil portion formed by extending the Xath loopcoil disposed in the proximity of the accommodation portion 11 is set tosuch a relationship as described hereinabove with reference to FIGS. 4Band 5 . Consequently, the magnetic fluxes Mfa and Mfb of differentdirections generated by the planar coil portion do not act uniformly onthe coil 21 of the electronic pen 2 accommodated in the accommodationportion 11.

Further, in the case of the position detection device 100B of the thirdembodiment, the control circuit 150 performs processing control similarto that performed by the control circuit 150 of the position detectiondevice 100A of the second embodiment described hereinabove withreference to FIG. 8 . However, the processes performed at S201, S204 andS206 depicted in FIG. 8 are a little different from those performed bythe position detection device 100A of the second embodiment.

In particular, in the position detection device 100B of the thirdembodiment, the control circuit 150 performs, at S201 and S204 depictedin FIG. 8 , the following processes. In particular, the control circuit150 first controls the selection circuit 113 to select the Xath loopcoil, which forms the planar coil portion, in the proximity of theaccommodation portion 11 and maintains the selection. Then, the controlcircuit 150 forms a control signal including alternate repetitions of anon period and an off period and supplies the control signal to theswitch circuit SW1. Further, within an off period, the control circuit150 controls the sample and hold circuit 133 of the position detectioncircuit 130 to operate.

In this manner, transmission and reception of a signal throughelectromagnetic induction through the Xath loop coil which forms theplanar coil portion in the proximity of the accommodation portion 11 arerepeated. If an induced voltage of a value equal to or higher than afixed value determined in advance is detected through the positiondetection circuit 130 within a reception period, then it can be detectedthat the electronic pen 2 is accommodated in the accommodation portion11. In contrast, if an induced voltage of a value equal to or higherthan the fixed value determined in advance is not detected through theposition detection circuit 130 within a reception period, then it can bedetected that the electronic pen 2 is not accommodated in theaccommodation portion 11.

Further, in the position detection device 100B of the third embodiment,the control circuit 150 performs the following process at S206 depictedin FIG. 8 . At S206, the control circuit 150 controls the selectioncircuit 113 to keep the state in which the Xath loop coil forming theplanar coil portion is selected and repeat transmission and reception ofa signal through the Xath loop coil. Accordingly, at S206, any one ofthe loop coils configuring the X-axis direction loop coil group 111 andthe loop coils configuring the Y-axis direction loop coil group 112 isnot selected except the Xath loop coil. Consequently, since a detectionprocess of a position indicated by the electronic pen 2 using theposition detection sensor 110 which is a main sensor is not performed,the power consumption can be reduced significantly.

Further, in this case, since the oscillation circuit 120, positiondetection circuit 130 and control circuit 150 are kept in an operativestate, if the electronic pen 2 is taken out from the accommodationportion 11, then this can be also detected. It is to be noted that, inthe state in which the electronic pen 2 is accommodated in theaccommodation portion 11, since the writing pressure detection circuit140 need not operate, operation of the writing pressure detectioncircuit 140 may be stopped.

The processes at S202, S203, S205, S207 and S208 are similar to thoseperformed by the position detection device 100A of the secondembodiment.

In this manner, in the case of the position detection device 100B of thepresent third embodiment, since one of the loop coils of a loop coilgroup configuring the position detection sensor 110 is extended toprovide a planar coil portion in the proximity of the accommodationportion 11, the accommodation sensor circuit for detecting whether ornot the electronic pen 2 is accommodated in the accommodation portion 11can be configured.

Further, in the case of the position detection device 100B of the thirdembodiment, the control circuit 150 can appropriately detect whether ornot the electronic pen 2 is accommodated in the accommodation portion 11making use of the Xath loop coil of the position detection sensor 110.Further, only when the electronic pen 2 is not accommodated in theaccommodation portion 11 but is in a used state, detection of a positionindicated by the electronic pen 2 and detection of a writing pressureapplied to the electronic pen 2 through the position detection sensor110 which is a main sensor can be performed. Consequently, when theelectronic pen 2 is accommodated in the accommodation portion 11, sincedetection of a position indicated by the electronic pen 2 and detectionof a writing pressure applied to the electronic pen 2 through theposition detection sensor 110 are not performed, reduction in powerconsumption can be anticipated.

Further, since the planar coil portion formed by extending the Xath loopcoil of the position detection sensor 110 is used as a sub sensor, thegap can be closed up fully and a waterproof specification can beachieved readily by using, for example, a waterproof sheet or the like.Further, since the planar coil portion formed by extending the Xath loopcoil of the position detection sensor 110 is used, in comparison with analternative case in which a coil formed in a spiral shape is used,complication of the fabrication process can be avoided and alsoreduction in thickness can be anticipated.

Effects of Embodiments

The position detection devices 100, 100A and 100B of the first, secondand third embodiments described hereinabove can achieve implementationof a waterproof specification, avoidance of complication in fabricationprocess and reduction in thickness of a mobile information terminal andcan implement also reduction of the power consumption. Consequently, aposition detection device and a control method for a position detectionsensor which can be suitably used together with a mobile informationterminal can be implemented.

Further, in the case of the position detection device 100 of the firstembodiment, since an accommodation sensor circuit which detects whetheror not the electronic pen 2 is accommodated in the accommodation portion11 can be configured separately from the position detection circuit, aposition detection device which can control them individually andreadily can be implemented.

Meanwhile, in the case of the position detection device 100A of thesecond embodiment, only by providing the planar coil 160A as a subsensor which detects whether or not the electronic pen 2 is accommodatedin the accommodation portion 11, both a position detection circuit andan accommodation sensor circuit can be configured, and the positiondetection device 100A which is simple in configuration can beconfigured.

Further, in the case of the position detection device 100B of the thirdembodiment, one of the loop coils in a loop coil group configuring theposition detection sensor 110 is used as a sub sensor which detectswhether or not the electronic pen 2 is accommodated in the accommodationportion 11. Consequently, the position detection device 100B which issimpler in configuration can be configured.

Modifications

While it is described in the embodiments described above that both aposition detection device of the electromagnetic induction type and aposition detection device of the capacitive coupling type areincorporated in the electronic apparatus main body 1, the presentdisclosure is not limited to this. Also where only a position detectiondevice of the electromagnetic induction type is incorporated, thepresent disclosure can be applied.

Further, the number of turns, shape and so forth of the planar coil 160or 160A or the planar coil portion formed using a loop coil configuringthe position detection sensor 110 as a sub sensor can be set suitably.For example, while the embodiments described above are directed to acase in which the planar coil 160 or 160A or the planar coil portionformed using a loop coil configuring the position detection sensor 110is formed in a rectangular shape, also it is possible to form the planarcoil 160 or 160A or the planar coil portion in an elliptical shape or ina circular shape.

Also it is possible to form the planar coil 160 or 160A or the planarcoil portion formed using a loop coil configuring the position detectionsensor 110 such that a portion thereof proximate to the coil 21 built inthe electronic pen 2 has a comparatively great width while a portionthereof remote from the coil 21 built in the electronic pen 2 has acomparatively small width. In other words, the planar coil 160 or 160Aor the planar coil portion formed using a loop coil configuring theposition detection sensor 110 may be formed in various shapes.

Further, the planar coils 160 and 160A and the loop coil Xa may each bedisposed at a position at which, from among magnetic fluxes generatedthereby, the magnetic fluxes directed in the opposite directions to eachother and interlinking with the coil 21 of the electronic pen 2accommodated in the accommodation portion 11 are not equal to each otherin number.

More preferably, the planar coils 160 and 160A and the loop coil Xa areeach disposed at a position at which only magnetic fluxes havingdirections same as each other interlink with the coil 21 of theelectronic pen 2 accommodated in the accommodation portion 11. In thiscase, the coil 21 of the electronic pen 2 accommodated in theaccommodation portion 11 may be positioned in the center axis directionof one portion of the planar coil 160 or 160A or the loop coil Xa so asto extend over the portion of the planar coil 160 or 160A or the loopcoil Xa as depicted in FIG. 4B.

Naturally, it is not an essential configuration that the coil 21 of theelectronic pen 2 is configured so as to extend over one portion of theplanar coil 160 or 160A or the loop coil Xa as depicted in FIG. 4B. Theplanar coil 160 or 160A or the loop coil Xa may be disposed at aposition at which, from among magnetic fluxes generated by the planarcoil 160 or 160A or the loop coil Xa, only those magnetic fluxes of thesame direction interlink with the coil 21 of the electronic pen 2.

While preferred embodiments of the present disclosure have beendescribed using specific terms, such description is for illustrativepurposes only, and it is to be understood that changes and variationsmay be made without departing from the spirit or scope of the followingclaims.

What is claimed is:
 1. A position detection device comprising: a mainbody with a housing that encloses an electronic pen while the electronicpen is accommodated in an accommodation portion included in the housing;and a planar coil having a rectangular cross-sectional area and disposedadjacent to the accommodation portion at a position at which a directionperpendicular to the rectangular cross-sectional area of the planar coilcrosses an axial direction of the electronic pen while the electronicpen is accommodated in the accommodation portion, wherein the electronicpen has a position indication coil wound in the axial direction of theelectronic pen, wherein the planar coil includes at least a first sideand a second side that is shorter than the first side, wherein, whilethe electronic pen is accommodated in the accommodation portion, thefirst side of the planar coil extends substantially in parallel to theaxial direction of the electronic pen, and wherein the planar coil ispositioned with respect to the accommodation portion such that, whilethe electronic pen is accommodated in the accommodation portion, acenter of the rectangular cross-sectional area of the planar coil in theaxial direction of the electronic pen is displaced with respect to acenter of the position indication coil in the axial direction of theelectronic pen.
 2. The position detection device according to claim 1,wherein: in operation, a first number of magnetic fluxes, from amongmagnetic fluxes generated by the planar coil, interlinking in a firstdirection with the position indication coil of the electronic pen is notequal to a second number of magnetic fluxes, from among the magneticfluxes generated by the planar coil, interlinking in a second directionwith the position indication coil of the electronic pen, the firstdirection being opposite the second direction.
 3. The position detectiondevice according to claim 2, wherein the planar coil is disposed at aposition at which only magnetic fluxes having same directions as eachother, from among the magnetic fluxes generated by the planar coil,interlink with the position indication coil of the electronic pen whilethe electronic pen is accommodated in the accommodation portion.
 4. Theposition detection device according to claim 2, wherein the planar coilis disposed, while the electronic pen is accommodated in theaccommodation portion, at a position at which a center axis direction ofthe planar coil passes through at least part of the position indicationcoil of the electronic pen or another position at which the positionindication coil of the electronic pen is displaced with respect to atleast part of the planar coil.
 5. The position detection deviceaccording to claim 1, further comprising: a first control circuit which,in operation, performs control such that a supply process in which afirst signal is supplied to the planar coil and a reception process inwhich a second signal is received through the planar coil byelectromagnetic induction are performed alternately; and a firstdetection circuit which, in operation, detects a state regardingaccommodation of the electronic pen in the accommodation portion inaccordance with a presence or an absence of the second signal receivedthrough the planar coil.
 6. The position detection device according toclaim 5, further comprising: a position detection sensor including aplurality of first loop coils disposed in a first direction and aplurality of second loop coils disposed in a second direction crossingthe first direction and configured to detect a position indicated by theelectronic pen in an operation region, the planar coil being disposedoutside of the operation region in which the position indicated by theelectronic pen is detectable by the position detection sensor; a secondcontrol circuit which, in operation, performs control to specify aspecified first loop coil which is to transmit a third signal from amongthe plurality of first loop coils and the plurality of second loop coilsand supply the third signal to the specified first loop coil, andspecify a specified second loop coil which is to receive a fourth signalfrom among the plurality of first loop coils and the plurality of secondloop coils and receive the fourth signal through the specified secondloop coil; a position detection control circuit which, in operation,controls, while the first detection circuit detects that the electronicpen is accommodated in the accommodation portion, at least the secondcontrol circuit to stop operating; and a second detection circuit which,in operation, detects the position indicated by the electronic pen onthe position detection sensor based on the fourth signal from thespecified second loop coil.
 7. The position detection device accordingto claim 6, wherein: the first control circuit and the second controlcircuit are configured as one control circuit; and the first detectioncircuit and the second detection circuit are configured as one detectioncircuit.
 8. The position detection device according to claim 6, wherein:the planar coil is formed using one of the plurality of first loop coilsand the plurality of second loop coils of the position detection sensor;the first control circuit and the second control circuit are configuredas one control circuit; and the first detection circuit and the seconddetection circuit are configured as one detection circuit.
 9. Theposition detection device according to claim 6, wherein the first andsecond loop coils are different from the planar coil.
 10. The positiondetection device according to claim 1, wherein a magnetic sheet or anelectromagnetic shield is disposed on one side of the planar coil.
 11. Acontrol method for a position detection sensor which is used for aposition detection device, the control method comprising: providing amain body with a housing that encloses an electronic pen while theelectronic pen is accommodated in an accommodation portion included inthe housing; and providing a planar coil having a rectangularcross-sectional area adjacent to the accommodation portion at a positionat which a direction perpendicular to the rectangular cross-sectionalarea of the planar coil crosses an axial direction of the electronic penwhile the electronic pen is accommodated in the accommodation portion,wherein the electronic pen has a position indication coil wound in theaxial direction of the electronic pen, wherein the planar coil includesat least a first side and a second side that is shorter than the firstside, wherein, while the electronic pen is accommodated in theaccommodation portion, the first side of the planar coil extendssubstantially in parallel to the axial direction of the electronic pen,and wherein the planar coil is positioned with respect to theaccommodation portion such that, while the electronic pen isaccommodated in the accommodation portion, a center of the rectangularcross-sectional area of the planar coil in the axial direction of theelectronic pen is displaced with respect to a center of the positionindication coil in the axial direction of the electronic pen.
 12. Thecontrol method according to claim 11, wherein: a first number ofmagnetic fluxes, from among magnetic fluxes generated by the planarcoil, interlinking in a first direction with the position indicationcoil of the electronic pen is not equal to a second number of magneticfluxes, from among the magnetic fluxes generated by the planar coil,interlinking in a second direction with the position indication coil ofthe electronic pen, the first direction being opposite the seconddirection.
 13. The control method according to claim 12, wherein theproviding the planar coil includes providing the planar coil adjacent tothe accommodation portion at the position at which a center axisdirection of the planar coil crosses the axial direction of theelectronic pen while the electronic pen is accommodated in theaccommodation portion.
 14. The control method according to claim 11,wherein the providing the planar coil includes providing the planar coilat a position at which only magnetic fluxes having same directions aseach other, from among the magnetic fluxes generated by the planar coil,interlink with the position indication coil of the electronic pen, whilethe electronic pen is accommodated in the accommodation portion.
 15. Thecontrol method according to claim 11, wherein the providing the planarcoil includes providing the planar coil at a position at which a centeraxis direction of the planar coil passes through at least part of theposition indication coil of the electronic pen or another position atwhich the position indication coil of the electronic pen is displacedwith respect to at least part of the planar coil, while the electronicpen is accommodated in the accommodation portion.
 16. The control methodaccording to claim 11, wherein a magnetic sheet or electromagneticshield is disposed on one side of the planar coil.
 17. The controlmethod according to claim 11, further comprising: performing a firstcontrol process that includes alternately supplying a first signal tothe planar coil and receiving a second signal through the planar coil byelectromagnetic induction; and detecting a state regarding accommodationof the electronic pen in the accommodation portion in accordance with apresence or an absence of the second signal received through the planarcoil extending substantially in parallel to an axis of the electronicpen while the electronic pen is accommodated in the accommodationportion.
 18. The control method according to claim 17, wherein: theposition detection sensor includes a plurality of first loop coilsdisposed in a first direction and a plurality of second loop coilsdisposed in a second direction crossing the first direction; and thecontrol method further comprises: performing a second control processthat includes specifying a specified first loop coil which is totransmit a third signal from among the plurality of first loop coils andthe plurality of second loop coils and supplying the third signal to thespecified first loop coil, specifying a specified second loop coil whichis to receive a fourth signal from among the plurality of first loopcoils and the plurality of second loop coils, and receiving the fourthsignal through the specified second loop coil; detecting the positionindicated by the electronic pen on the position detection sensor basedon the fourth signal received through the specified second loop coil;and controlling, while detecting that the electronic pen is accommodatedin the accommodation portion, to not perform the second control processand the detecting of the position indicated by the electronic penthrough the position detection sensor.
 19. The control method accordingto claim 11, wherein the position detection sensor includes a pluralityof first loop coils disposed in a first direction and a plurality ofsecond loop coils disposed in a second direction crossing the firstdirection and configured to detect a position indicated by theelectronic pen in an operation region, the planar coil being disposedoutside of the operation region in which the position indicated by theelectronic pen is detectable by the position detection sensor.
 20. Thecontrol method according to claim 19, wherein the first and second loopcoils are different from the planar coil.